JP2010276952A - Method of manufacturing urethane foam roller for electrophotography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a urethane foam roller with skin layer for electrophotography, by which the skin layer is formed on the surface of the urethane foam, when manufacturing the urethane foam roller for electrophotography by using a cylindrical mold, and stable mold releasability is secured. <P>SOLUTION: The manufacturing method for the urethane foam rubber for electrophotography is characterized in that a mold release agent which contains at least one or more types of wax components and does not contain silicone oil components is selected as the mold release agent to be applied on the inner surface of the cylindrical mold, and the mold-release of the urethane foam roller from the mold is performed at the temperature of wax melting point or higher. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a urethane foam roller used in an electrophotographic apparatus. Specifically, the present invention relates to a method for stably producing a urethane foam roller having a skin layer on the surface and having an appropriate hardness by foaming and suitable as a charging roller, a developing roller, and a transfer roller, using a cylindrical mold. is there.

  With the advancement of electrophotographic technology, image forming apparatuses such as dry electrophotographic apparatuses are made of a polymer material having rubber elasticity as a component member used for charging, developing, transferring, toner supplying, etc. Including members are attracting attention. This member is used in the form of a roller such as a charging roller, a developing roller, a transfer roller, or a toner supply roller.

  Due to the demand for high-definition and high-quality electrophotography, the use of polyurethane materials is increasing for electrophotographic roller members in order to reduce stress on toner and improve the quality of reproduced images. Furthermore, the application of urethane foam is increasing for the purpose of reducing material costs and reducing hardness by foaming.

  For example, in an elastic member for an image forming apparatus such as a charging roller and a developing roller, it is necessary to improve the ground contact accuracy with the photosensitive drum for uniform charge application and toner transportability. However, if there are large open cells on the surface of the urethane foam elastic member, there is a case where the charge application and the toner coat in this portion become non-uniform and image defects occur. Even if some coating layer is provided on the urethane foam elastic layer, it may be difficult to cancel the shape of the underlying elastic layer when the coating layer component is applied by dipping or spraying. Also, if the coating layer is a tube body and the method is to coat this, there is no problem even if there are open cells on the surface of the urethane foam elastic layer, but the urethane surface is tacky and it is difficult to coat the tube. .

  Therefore, it is preferable that there is no open cell on the surface of the urethane foam elastic layer and a skin layer is formed.

  Urethane foam rollers having a skin layer are introduced in Patent Documents 1 to 4, and the like.

JP-A-8-166695 JP-A-8-166732 JP-A-8-305132 JP 2001-304245 A

  However, in Examples described in Patent Document 1 to Patent Document 4 and the like, urethane foam material was poured into a mold incorporating a metal shaft, and after heat curing, the urethane foam roller having a skin layer was obtained by demolding. It remains to state.

  When producing a urethane foam roller having a skin layer, the material is often poured into a mold having a shaft as described above, and demolded after thermosetting. At this time, the inner surface of the mold is subjected to a mold release process for facilitating demolding. When this treatment is inappropriate, open cells appear on the surface of the urethane foam. Moreover, since the urethane material has tackiness on the surface, it is difficult to peel the urethane foam from the inner surface of the mold. In the case of urethane foam in which bubbles are connected in a sponge shape, the mold and the urethane foam can be separated by moving the shaft in the circumferential direction of the mold. However, it is very difficult to remove the roller from the mold if it is not connected or if the foaming ratio is low and there is no room for deformation of the foam even if the shaft is moved in the circumferential direction of the mold.

  The present invention relates to a method for producing a urethane foam roller for electrophotography made in view of the above-mentioned problems. The object of the present invention is to produce a urethane foam roller for electrophotography obtained by foaming and curing a urethane foam material using a mold having a release agent applied to the inner surface, while building a skin layer on the surface, It is to provide a production method capable of obtaining good demolding property.

The method for producing an electrophotographic urethane foam roller according to the present invention includes:
A molding die comprising a cylindrical die and a piece disposed at both ends of the cylindrical die and provided with holes for supporting the shaft core and injecting material is used, and is separated from the inner surface of the die. Applying a mold; and
Disposing an axial core in the mold cavity;
Injecting urethane foam material into the mold cavity;
Foaming and curing the urethane foam material;
Removing a urethane foam roller in which a layer made of a cured product of the urethane foam material is formed on the shaft core body from the mold;
In the process for producing a urethane foam roller for electrophotography with a skin layer having
The release agent contains at least one kind of wax and does not contain silicone oil, and in the step of removing the urethane foam roller from the molding die, the temperature of the molding die is equal to or higher than the melting point of the wax. It is characterized by.

  Production of urethane foam roller for electrophotography with skin layer, which makes it difficult to remove stably due to frictional resistance between the inner surface of the mold and the skin layer on the surface of urethane foam and surface tackiness specific to urethane material. It is possible to obtain a good demolding property in the method.

It is sectional drawing of the urethane foam roller for electrophotography which concerns on this invention.

  The present inventors have studied to achieve the above object, and have found that the mold release treatment applied to the inner surface of the mold affects the skin layer formation. Furthermore, in addition to the tackiness peculiar to urethane, as a result of examining how to remove the urethane foam roller, which has become more difficult to remove due to increased frictional resistance with the inner surface of the mold due to the formation of a skin layer, The present invention has been reached.

That is, the present invention is a urethane in which a urethane foam material is foamed and cured using a molding die coated with a release agent on the inner surface, and a layer made of a cured product of the urethane foam material is formed around the shaft core body. In a method for producing an electrophotographic urethane foam roller with a skin layer, which is obtained by molding a foam roller and taking out the urethane foam roller from a molding die.
The mold release agent contains at least one kind of wax and does not contain silicone oil, and in the step of removing the urethane foam roller from the molding die, the temperature of the molding die is equal to or higher than the melting point of the wax. It has the characteristics.

  One embodiment of the method for producing a urethane foam roller for electrophotography with a skin layer of the present invention is as follows.

That is, the following steps (i) to (v):
(I) using a molding die having a cylindrical die and a piece disposed at both ends of the cylindrical die and having a hole for supporting a shaft core and injecting a material; Applying a release agent to the inner surface;
(Ii) a step of disposing the shaft core body in the molding die cavity;
(Iii) injecting urethane foam material into the mold cavity;
(Iv) foaming and curing the injected urethane foam material, and molding a urethane foam roller in which a layer made of a cured product of the urethane foam material is formed on the shaft core;
(V) a step of taking out the urethane foam roller from the molding die;
Have
The mold release agent contains at least one kind of wax and does not contain silicone oil, and in the step of removing the urethane foam roller from the molding die, the temperature of the molding die is equal to or higher than the melting point of the wax. Characterized by the
This is a method for manufacturing a urethane foam roller for electrophotography with a skin.

  Hereinafter, specific modes of the present invention will be described in the order of steps.

  The mold according to the present invention uses a mold having at least three parts, a cylindrical mold, and a piece disposed at both ends of the mold and provided with a hole for supporting a shaft core and injecting a material. . As the molding die having such a cylindrical die and a piece, those conventionally used as a die for molding a urethane foam roller can be used. The hole provided in the piece is not particularly limited as long as it can secure a gap for injecting the material after supporting the shaft core, and the hole for injecting the material is a hole for supporting the shaft core. It may be provided in a connected manner, or may be provided at a position separate from the hole for the shaft core. Moreover, conventionally known materials and shapes can be used, but the inner surface of the cylindrical mold is preferably smooth, and specifically, the surface roughness Ra is preferably within 1 μm. When the inner surface of the cylindrical mold is rough, it is difficult to obtain a skin layer, and the frictional resistance at the time of roller demolding tends to increase, so that demolding tends to be difficult.

  As the shaft core body of the present invention, a conventional shaft core body for an electrophotographic urethane foam roller can be used, and the outer diameter is preferably 2 mm or more and 10 mm or less. The material of the shaft core is not particularly limited, and examples thereof include a metal member obtained by plating a steel material such as sulfur free cutting steel with nickel or the like, or a metal member such as aluminum, stainless steel, or magnesium alloy. A known adhesive layer such as an adhesive or a hot melt sheet can be provided on the surface of the shaft core as necessary.

  The release agent of the present invention needs to contain at least one kind of wax and no silicone oil. Although the wax does not interfere with the skin layer, the silicone oil functions as an antifoaming agent. Therefore, if the release agent contains silicone oil, the surface of the urethane foam opens.

  There is no restriction | limiting in particular in the wax component used here, It can select and use from conventionally well-known various waxes suitably. For example, a natural or synthetic wax such as montan wax, montanic acid ester wax, microcrystalline wax, paraffin wax, carnauba wax, bead wax, polyethylene wax, or a combination of one or more of these may be used. Among them, the lubricity when paraffin wax is melted is preferable and preferable.

  The melting point of the wax is preferably 45 ° C. or higher and 120 ° C. or lower. When the melting point of the wax is too high, if the temperature of the inner surface of the mold is set higher than the melting point of the wax, the expansion of the urethane foam tends to increase, and the frictional resistance between the inner surface of the mold and the urethane foam tends to increase, making it difficult to remove the mold. There is. If the melting point of the wax is too low, the wax tends to melt due to the material temperature injected into the mold cavity and the reaction heat of the urethane, and the surface of the roller tends to become rough due to mixing with the uncured urethane foam material. By setting the melting point of the wax in the range of 45 ° C. or more and 120 ° C. or less, stable roller molding is possible.

  Wax can be diluted with various solvents in order to improve its coatability. The solvent at this time may be water or an organic solvent. In the case of dissolving, dispersing or emulsifying and dispersing in water, conventionally known dispersants and emulsifiers can be used. Examples of the organic solvent include hydrocarbon solvents such as industrial gasoline and petroleum naphtha. However, at this time, silicone oil should not be used as an additive. Here, the silicone oil corresponds to one that acts as an antifoaming agent in the process of foaming and curing the urethane foam, and includes, for example, a linear silicone molecule having a siloxane bond of 2000 or less.

  The viscosity of the release agent is preferably 1 mPa · s or more and 1,000 mPa · s or less at 25 ° C. When the viscosity is within these ranges, it is possible to have a good coating property to the mold.

  The release agent may be applied by a conventionally known method. For example, the release agent is immersed in a mold, sprayed, brushed, etc., or sprayed after being aerosolized, or applied by soaking into a cloth. Then, the medium may be removed by evaporation.

  The urethane foam layer of the present invention is formed from a urethane raw material containing at least a polyol and an isocyanate.

  There is no restriction | limiting in particular as a polyol, It can select and use suitably from conventionally well-known various polyols. For example, as a polyol component constituting such a liquid polyurethane raw material, those generally used in the production of flexible polyurethane foams can be used. That is, it can be appropriately selected from known polyols such as polyether polyols, polyester polyols, polymer polyols, etc., and may be used alone or in combination of two or more.

  Of the above polyols, the use of polyether polyol is suitable for the production of a soft and highly elastic polyurethane excellent in moisture and heat resistance. Further, a prepolymer previously polymerized with polyisocyanate may be used.

  Moreover, there is no restriction | limiting in particular as polyisocyanate, It can select and use suitably from conventionally well-known various polyisocyanate. For example, 2,4- and 2,6-tolylene diisocyanate (TDI), tolidine diisocyanate (TODI), naphthylene diisocyanate (NDI), xylylene diisocyanate (XDI), 4,4'-diphenylmethane diisocyanate (MDI), and carbodiimide Modified MDI, polymethylene polyphenyl polyisocyanate, and polymeric polyisocyanate may be used alone or in combination of two or more. In addition, the isocyanate group terminal prepolymer obtained by making polyisocyanate react with 1 type, or 2 or more types of a well-known active hydrogen compound can also be used as polyisocyanate.

  The NCO index of the polyurethane raw material is preferably 60 or more and 120 or less, and more preferably 70 or more and 110 or less. The NCO index is a value obtained by dividing the total number of isocyanate groups in the polyisocyanate by the total number of active hydrogens that react with the isocyanate groups and multiplying by 100. That is, when the number of active hydrogens reacting with an isocyanate group and the isocyanate group in the polyisocyanate are stoichiometrically equal, the NCO index is 100.

  Moreover, as another raw material for urethane foam, although it may use suitably as needed, the following examples are given.

  There is no restriction | limiting in particular as a catalyst, It can select from the conventionally well-known various catalysts suitably, and can be used. Conventionally known catalysts such as triethylenediamine, dimethylethanolamine and bis (dimethylamino) ethyl ether can be used.

  There is no restriction | limiting in particular as a foam stabilizer, It can use suitably selecting from conventionally well-known various foam stabilizers. For example, SRX-274C (trade name) manufactured by Toray Dow Corning, L3640 (trade name) manufactured by Momentive Performance Materials, etc. can be used as the silicone surfactant.

  Further, other components can be added to the polyurethane raw material in which these polyol component and polyisocyanate component are blended, as in the conventional case. For example, the cross-linking agent, foaming agent (water, low-boiling substances, gas body, etc.), foam breaker, etc. are the target polyurethane foam layer structure after foam molding, that is, either open cell type or closed cell type It is added so that it may become a well-known mixing | blending which is easy to produce a reactive foaming raw material. In addition, known materials such as a conductivity-imparting agent and an antistatic agent for imparting desired conductivity may be added to such raw materials as necessary. As the conductivity-imparting agent, known ones can be used. For example, conductive metal oxides such as carbon black, graphite, titanium oxide and tin oxide, metals such as copper and silver, and these conductive materials on the particle surface. For example, particles coated and made conductive. These conductivity-imparting agents can be used alone or in combination. In particular, carbon black is preferable in that desired conductivity can be imparted by addition of a relatively small amount (weight ratio). As other additives, flame retardants, thickeners, pigments, stabilizers, colorants, anti-aging agents, ultraviolet absorbers, antioxidants, antioxidants and the like can be blended as necessary. Examples of the crosslinking agent include conventionally known ones such as triethanolamine and diethanolamine.

  The method for producing an electrophotographic urethane foam roller of the present invention is not particularly limited, and may be a conventional method. An example is as follows. First, an organic solvent release agent is uniformly applied to the mold in a sponge and heated to 45 ° C. and dried. The heat drying temperature is preferably less than the melting point of the release agent, and it is preferable to sufficiently dry the release agent application surface. Therefore, the method for producing a urethane foam roller for electrophotography according to the present invention is a state in which moisture does not remain in the release agent film applied to the mold sub-inner surface before the step of injecting the urethane foam material into the mold cavity. It is desirable to have a drying step. The release agent can be dried by evaporation by heat or ventilation by a ventilation means. After preparing the urethane raw material by uniformly mixing the polyether polyol, polyisocyanate, catalyst, foam stabilizer, water, and other auxiliary agents used as required, this is poured into a mold and heated to react and cure. Thus, a urethane foam can be formed.

  The temperature and time for mixing the urethane raw material are not particularly limited, but the mixing temperature is usually 10 ° C. or higher and 90 ° C. or lower, preferably 20 ° C. or higher and 60 ° C. or lower, and the mixing time is usually 1 second or longer. 10 minutes or less, preferably 3 seconds or more and 5 minutes or less.

  The temperature of the mold and the urethane foam material when injecting the urethane foam material into the mold cavity is preferably lower than the melting point of the wax. By setting the temperature of the mold and the urethane foam material to a temperature lower than the melting point of the wax, it becomes difficult for the wax to mix with the urethane foam material, and a good skin layer can be obtained without roughening the surface of the urethane foam.

  There is no particular limitation on the injection speed when injecting the urethane foam material into the mold cavity. Usually, for example, when a urethane foam layer having a thickness of 2 to 6 mm is provided on a shaft core having a diameter of 4 to 10 mm and a length of 200 to 400 mm, the injection speed is infused at a rate of 2 cc / sec to 20 cc / sec. It is preferable to do. By setting it as this range, generation | occurrence | production of a void and foaming nonuniformity of urethane foam can be suppressed.

  The mold temperature during foaming and curing is preferably 45 ° C. or higher and 120 ° C. or lower. The foaming method is not particularly limited, and any method such as a method using a foaming agent or a method of mixing bubbles by mechanical stirring can be used. The expansion ratio may be determined as appropriate and there is no particular limitation.

  When taking out the urethane foam roller from the mold, the temperature of the mold needs to be higher than the melting point of the wax. If the mold temperature is lower than the melting point of the wax, sufficient lubricity cannot be obtained, and demolding becomes difficult. As a demolding method, the urethane foam adhered to the outer periphery of the shaft core body can be demolded by pressing the shaft core body exposed from both ends of the cylindrical mold. However, when the lubricity by the mold release agent is insufficient, the removed urethane foam roller may crack, or only the shaft core body may come off while leaving the urethane foam in the mold. .

  The urethane foam roller for electrophotography of the present invention has a skin layer on the surface. Thanks to the skin layer, the roller surface becomes smooth, and when the electrophotographic urethane foam roller is used as a charging roller or a developing roller, uniform charge application and toner transportability can be obtained. When the mold temperature is higher than the melting point of the wax, the wax is liquefied and the lubricity increases compared to when the wax is solid, greatly increasing the frictional resistance between the inner surface of the mold and the skin layer of the roller during demolding. Can be reduced.

  FIG. 1 is a sectional view showing an example of an electrophotographic urethane foam roller of the present invention. As shown in FIG. 1, the electrophotographic urethane foam roller includes a cylindrical shaft core A and a urethane foam layer B provided around the shaft core A except for both ends of the shaft core A. The foam cell in the urethane foam can be selected from open cell type, closed cell type, or a mixed system of both. The surface of the urethane foam layer B has a skin layer C.

  The electrophotographic urethane foam roller of the present invention may be provided with a conductive, semiconductive, or insulating coating layer depending on the application. The urethane foam roller for electrophotography of the present invention is not particularly limited as long as its use is for an image forming apparatus, but can be used for, for example, a charging roller, a developing roller, a transfer roller, and the like.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to these examples.

The jigs and materials used for producing the urethane foam roller are shown below.
・ Cylindrical mold: inner diameter φ12, outer diameter φ26, length 230 mm, material SUS304, nickel chrome plating ・ Shaft core: outer diameter φ6, length 240 mm, material SUS303, nickel chrome plating Description / Urethane foam material Mixed polyol Polyol: FA-718 (manufactured by Sanyo Chemical Industries, Ltd .: trade name)
Hydroxyl value = 28 [mg KOH / g] 100 parts by mass Foam stabilizer: L3640 (Momentive Performance Materials
Made by Japan Godo Kaisha: Trade name) 1 part by mass Catalyst: TOYOCAT-ET (product of Tosoh Corporation: trade name) 0.3 part by weight
TEDA-L33 (manufactured by Tosoh Corporation: trade name) 0.5 part by mass Foaming agent (water) 0.5 part by mass Polyisocyanate Coronate 1021 (manufactured by Nippon Polyurethane Industry Co., Ltd .: trade name)
Isocyanate group content = 44.5 [%] 9.7 parts by mass The above-described polyol components (polyol, foam stabilizer, catalyst, water, etc.) were mixed with a hybrid mixer HM-500 (manufactured by Keyence Corporation: trade name). Was mixed for 3 minutes to obtain a mixed polyol material. This and polyisocyanate were set in each raw material tank of the injection apparatus, and the temperature was adjusted so that the material temperature was 45 ° C.

  The cylindrical mold and the pieces to be incorporated at both ends are heated to 45 ° C. The cylindrical mold is soaked with a release agent in the sponge, and the pieces are immersed in the release agent to remove the mold. The agent was removed by blowing compressed air. Thereafter, the mold was heated by heating at 45 ° C. for 30 minutes. Further, a shaft core body was incorporated and heated at 45 ° C. for 30 minutes to preheat the mold and the shaft core body.

  The discharge ratio of the mixed polyol material and the polyisocyanate was adjusted so that the NCO index was 100, and the urethane foam material was injected into a mold cavity heated to 45 ° C. for 5 seconds at 3 cc / second. The mold was sandwiched between SUS mold temperature control hot plates adjusted to 60 ° C. and foamed and cured for 5 minutes. Next, in order to set the temperature at the time of demolding to the conditions shown in Table 1, heating and cooling were performed using another mold temperature control hot platen, and demolding was performed when the temperature reached the conditions.

Comparative Example 5 is a mixture of M933 and URS-92 in a mass ratio of 50:50. Details of the release agent types in Table 1 are as follows.

M933 (): Wax release agent (manufactured by Chukyo Yushi Co., Ltd.)
N849: Wax release agent (manufactured by Chukyo Yushi Co., Ltd.)
N915: Wax release agent (manufactured by Chukyo Yushi Co., Ltd.)
URS-92: Silicone mold release agent (manufactured by Konishi Co., Ltd.)
Flease 610: Fluorine mold release agent (Neos Co., Ltd.)
In Examples 1 to 6 according to this example, the component of the release agent contains a wax component and does not contain a silicone oil component, and the temperature at the time of demolding is equal to or higher than the melting point of the wax. A skin layer was formed and good demoldability was obtained.

  On the other hand, in Comparative Examples 1 to 3, since the temperature at the time of demolding was less than the melting point of the wax, the frictional resistance at the time of demolding was large, and the mold was sometimes demolded with cracks in the urethane foam. Regarding Comparative Examples 4 and 5, since the silicone oil component was included in the release agent, the urethane foam surface opened and a skin layer was not obtained. As in Comparative Examples 1 to 3, Comparative Example 6 was sometimes demolded in a state where the urethane foam was cracked.

A: Shaft core B: Urethane foam layer C: Urethane skin layer

Claims (5)

A molding die comprising a cylindrical die and a piece disposed at both ends of the cylindrical die and provided with holes for supporting the shaft core and injecting material is used, and is separated from the inner surface of the die. Applying a mold; and
Disposing an axial core in the mold cavity;
Injecting urethane foam material into the mold cavity;
Foaming and curing the urethane foam material;
Removing a urethane foam roller in which a layer made of a cured product of the urethane foam material is formed on the shaft core body from the mold;
In the process for producing a urethane foam roller for electrophotography with a skin layer having
The mold release agent contains at least one kind of wax and does not contain silicone oil, and in the step of removing the urethane foam roller from the molding die, the temperature of the molding die is equal to or higher than the melting point of the wax. A method for producing a urethane foam roller for electrophotography with a skin layer.   The method for producing a urethane foam roller for electrophotography with a skin layer according to claim 1, wherein the wax has a melting point of 45 ° C. or higher and 120 ° C. or lower.   The method for producing a urethane foam roller for electrophotography with a skin layer according to claim 1, wherein the wax is paraffin wax.   The electrophotographic film with a skin layer according to any one of claims 1 to 3, wherein a temperature of the mold and the urethane foam material when the urethane foam material is injected into the mold cavity is lower than a melting point of the wax. Urethane foam roller manufacturing method.   5. The method according to claim 1, further comprising a step of drying the mold release agent film applied to the inner surface of the mold so that no moisture remains before the step of injecting the urethane foam material into the mold cavity. A method for producing a urethane foam roller for electrophotography with a skin layer as described above.

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